MISFIRE #4 CYLINDER

Jaguar XJ8

I have 99 vanden plas.
misfire #4 cylinder.
was getting 4 misfire codes I changed ignition coils, plugs
after computer I still get the 1 misfire.
have cleaned fuel injector directly and also with fuel additive.
The car has 53000 miles. Any ideas?
By the way, even when throwing 4 misfire codes only the #4 was specified.
Thanks,
cbgb

I also have this problem it is cylinder 3 misfiring The car is throwing codes P0303 misfire detected cyl #3 and P1313 " Manufacturer Contrl. Ignition system or misfire" and P1316 " Manufacturer Contrl. Ignition system or misfire" Please help thanks in advance. I think it is the ignition module or EGR system.

I had changed what I thought was #4 coil, which is the one specified by diagnostics.
Not being familiar with British engines, I changed wrong coil.
After months of head scratching, fooling with fuel injectors, computer, air flow, etc. I realized I had changed wrong coil.
Put new coil in #4 and now runs Beautifully.
At one point was throwing 7 or 8 codes, all attributed to this one coil misfire.